Pharmaceutical Bilayer Tablets

Three-dimensional printing was used for the production of bilayer tablets. Hydroxypropyl methyl cellulose and poly(acrylic add) were used as a hydrophilic matrix for the formation of a sustained release layer. The drug release is comparable with commercial counterparts. 

The printed formulations were also evaluated for a variety of weight, friability, hardness, and thickness. Also, the release rate was investigated. This can be done by using the Korsmeyer-Peppas equation (56-58). The Korsmeyer-Peppas equation reads as 

Q is the amount of agent released at time f, Qo is the total amount released. A is a release constant and n is the order, b is the axis intercept, characterizing the initial burst release mechanism. The exponent n is related to the dissolution mechanism. For example, n = 1 characterizes an erosion controlled mechanism (59). 

In the case of the above-mentioned pharmaceutical bilayer tablets, Korsmeyer-Peppas n values between 0.27 and 0.44 were observed, which indicates a Fickian diffusion governed drug release (60). 

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